The present invention broadly concerns methods and apparatus for storing and retrieving data on a tape medium. More specifically, the present invention concerns tape threading apparatus on tape transport apparatus. The invention particularly concerns a leader block that positively locks onto a leader pin of a tape transport medium. The invention also concerns a method of threading the tape medium through the tape transport apparatus using such a leader block.
The advent of the computer has already had a profound effect upon human society, and the impact of processing technology is expected to increase. Indeed, the desirability to store information for subsequent retrieval currently grows at an exponential rate. Thus, various types of devices have been developed to store data both for on-line usage as well as for archival purposes.
Where on-line processing requires data to be readily at hand, a significant improvement was provided by the advent of the magnetic disk storage array. Here, one or more magnetic disks are provided, and a read/write recording head is used to record information on the disk as well as to retrieve information or data for use by the computer processor. Significant strides have been made in the ability to increase the density of data stored on such magnetic disk arrays. In order to gain an even higher density for on-line data, the optical disk was developed. These devices record data based upon a very small wavelength of light so that a higher density is obtained due to this technique. Laser light is employed to read the stored information or data on the optical disk.
In early days of the computer, before the advent of the magnetic disks and the optical disk storage assemblies, data was typically stored on magnetic tapes, such as reel-to-reel tapes and later cassettes. In a magnetic tape storage device, a magnetic coil is used as a transducer to imprint data magnetically on a moving band of magnetic film; thereafter, when the film is advanced across the transducer, the data may be read and re-input into a co-processor. Magnetic tape can be erased and rewritten many times and has an advantage of low cost.
Magnetic tape is still a highly desirable format for archiving data for rapid access is of less significance and cost is of concern. However, where vast quantities of data are to be maintained, these tapes can be bulky due to the physical number necessary to store the quantity of data. The capacity for such tapes to store data, of course, is dependent upon the number of xe2x80x9ctracksxe2x80x9d which can be independently placed across the width of the tape.
The ability to write data rapidly onto a magnetic tape film and the accessibility of data to be read from the film is a function of two variables: (1) the density of storage; and (2) the speed at which the tape medium may be transported across and accurately written/read by the transducer. Thus, for example, a magnetic tape read/write system that is able to read and write nine tracks of data on a single strip of tape will hold four and one-half times the amount of data as a system which only utilizes two tracks. Therefore, efforts to increase the capacity of magnetic tapes to store data have included substantial efforts to increase the number of tracks which can be written on a band of magnetic tape.
In the above-described systems, storage reels of tape, whether flanged or flange-less (for example as used in cartridges) may be placed on the machine during use. A threading assembly engages the free end of the tape and passes it through the machine. Typically, the tape is threaded across air bearings, past the transducer and into a take-up hub or reel. The length of the tape is then passed through the machine so that information may be placed on the tape or retrieved therefrom. During this process, the length of tape is transferred onto a take-up reel or hub that is either a part of the machine itself, included within the cartridge or that is mounted and de-mounted from such machine. After being transported through the machine, the tape may be rewound onto the storage reel and removed from the machine.
As was explained in my earlier U.S. Pat. No. 5,777,823, issued Jul. 7, 1998, it is important that the lateral edge of the tape moving in a transport direction be properly registered along a reference plane, called the datum, so that the data may be accurately input and retrieved from the tape medium. Support of the tape during transport is therefore critical, and typically employs guide rollers, air bearing and the like as is known in the art. Improved air bearings are the subject of U.S. Pat. No. 5,777,823 and U.S. patent application Ser. No. 10/111,728 filed Apr. 26, 2002 (priority date Oct. 28, 1999), the disclosures of which are hereby incorporated by reference. It is also important that the read/write head be accurately positionable. A representative structure for such positioning is shown in U.S. Pat. No. 6,078,478, the disclosure of which is hereby incorporated by reference.
Take-up reels are typically constructed to have a central hub that has annular flanges and a width slightly greater than the width of the tape. It is also known to use flange-less hubs in winding tape media. In either case, the hub is rotated about a central winding axis, and the length of tape is wrapped circumferentially around the hub.
Many tape drives utilize a tape source in the form of a cartridge which may be mounted or demounted into the recording and reading apparatus. These cartridges typically contain a spool of tape media upon which information may be stored. The tape media is then transported across the read/write recording head either to place data on a blank tape which you override existing data, as is the case with a xe2x80x9cwritexe2x80x9d operation or, alternatively, to retrieve information that already exist on the tape media during the xe2x80x9creadxe2x80x9d state. In either case, the tape is typically attached to a leader pin that is adapted to be engaged by a leader block that is part of the threading mechanism. The threading mechanism engages the leader pin by means of the leader block, and then mechanically threads the tape across air bearings that ore disposed on either side of read/write recording head. The threading mechanism conveys the leader block to a take-up hub.
Traditional leader blocks engage the leader pin of a tape medium from the side, that is, laterally. Thus, traditional leader blocks rely upon constant tension of the tape medium in order to maintain an engaged relationship. This presents a problem in several respects. On one hand, if the leader pin is improperly parked in the tape cartridge, the leader block may not even be able to engage the leader pin to withdraw the tape from the cartridge. In the event that the leader block does engage the leader pin and begins to pull the tape from the cartridge, misregistration of the leader pin in the leader block can result in the leader block""s dropping the leader pin during the threading operation. Once the leader pin is lost, it cannot be recovered by the threading apparatus so that the equipment must be serviced or repaired. Not only is this expensive in cost due to the cost of repairs and down time, the lost leader pin can damage the read/write apparatus.
Even where the leader block properly engages the leader pin, there is still always the risk that some other event will cause a release of tension on the tape medium. For example, if a power outage occurs, tension is lost and the leader pin can fall out of the leader block. This results in the same issues of repair and damage noted above.
Accordingly, there is a need for an improved leader block assembly which can selectively releaseably engage the leader pin in a positive manner. There is need for a leader block that can positively engage the leader pin for virtually all types of threading assemblies and for the use of such a leader block in a tape transport apparatus. The present invention is directed to meeting these needs.
It is an object of the present invention to provide a new and useful leader block that may be used in threading assemblies on tape transport apparatus.
It is another object of the present invention to provide a new and useful method of threading a tape medium from a tape source through a read/write recording apparatus.
A further object of the present invention is to provide a leader block and method that positively engages the leader pin on the free end of a tape from a tape source, such as a tape cartridge.
Yet another object of the present invention is to provide a leader block that releaseably latches onto a leader pin so that the leader pin cannot be dropped in the event of loss of tension of tape during a tape threading operation.
Still a further object of the present invention is to provide a leader block that releaseably latches onto a leader pin wherein the leader pin may be controllably disengaged from the leader block only upon mechanically actuation thereof.
Yet another object of the present invention is to provide a leader block that will assist in re-parking a leader pin within a tape cartridge prior to engaging it so that a positive latching of the leader pin is accomplished by the leader block.
It is still a further object of the present invention to provide a leader block assembly that is simple in construction and easy to manufacture yet which positively engages a leader pin throughout the threading operation.
According to the present invention, then, a leader block is provided that is adapted to be advanced in a first direction to engage a leader pin on a tape medium. Broadly, the leader block comprises a body member and a latch member disposed on the body member. The latch member includes a catch piece that is relatively moveable with respect to the body member between an open position to permit engagement and disengagment with the leader pin and a closed position to retain the leader pin when the leader pin is engaged therein. The leader pin according to the present invention can be incorporated into a threading assembly that in turn is incorporated into a read/write apparatus. Both the threading assembly and the read/write apparatus make up additional aspects of the present invention.
Whether viewed as the leader block alone or in combination with a threading assembly or in combination with a read/write apparatus, the leader block of the present invention may have a leading edge portion that includes a pair of spaced apart engagement structures that are operative to engage the leader pin. The latch member then includes a pair of catch pieces that are respectively associated with the engagement structures. Whether one or a plurality of catch pieces are provided, they are biased toward the closed position. The engagement structures may include at least one stationary finger. Here, each catch piece cooperates with a respective finger to form an enclosed area when in the closed position yet forms an open area with an entryway when in an open position. However, it is preferred that the engagement structures include a pair of stationary fingers defining a slot therein.
In order to facilitate engagement of the catch piece with the leader pin, the catch piece includes a leading ramp portion that is operative to attack the leader pin as the leader block is moved in the first direction thereby to move the catch piece in the open position. There after, the catch piece, due to the biasing thereof, snap locks into the closed position about the leader pin. The catch piece may include an arcuate trailing edge portion so that, once it is in the closed position, the catch piece cannot become disengaged from the leader pin until positive actuation of the catch piece occurs.
In its more detailed presentation the leader block of the present invention includes a latch member in the form of a channel shaped piece in which the body member is nested. The body member includes first and second spaced apart engagement structures disposed on the leading edge portion with each of these engagement structures formed as a pair of stationary fingers having a slot therebetween. The latch member is pivotably disposed on the body member and includes first and second arms that terminate in catch piece with each catch piece being associated with respective one of the first and second engagement structures. The latch member is relatively movable with respect to the body member between an open position to permit each catch piece to interact with a respective finger to engage with and disengage from the leader pin. When in the open position, the latch member is spring biased toward the closed position with a restorative force. When in the closed position, the leader pin is retained in the leader block.
The latch member can include a central panel piece as it extends between the first and second arms thereby to form a channel structure within which the body member is nested. The spring piece may be formed as a wing that extends from the central panel piece and confronts the body member and flexes as the latch member pivots to the open position. The first and second arms, the central panel piece and the wing are preferably formed as a integral one-piece construction of a spring steel or other metal construction. The latch member is pivoted relative to the body member by means of an axial pin that is received in trunion mounts on each of the first and second arms. The latch member can include an actuator tab that is operative under an actuator force to pivot the latch member from the closed position to the open position against the restorative force.
The threading assembly according to the present invention includes one or more of the elements of the leader block structure described above. In addition, the threading assembly includes a primary guide track and a flexible conveyor member received in the primary guide track. A motor is then operative to reverseably drive the conveyor member in first and second directions. The leader block is secured to the conveyor member. In the exemplary embodiments, the conveyor member is selected from a group consisting of chains and belts. The threading assembly of the present invention may also include a secondary guide track formed as a mirror image of the primary guide track. The secondary guide track receives a portion of the leader pin therein for sliding movement as the conveyor member is driven in the first and second direction.
The threading assembly of the present invention also includes an actuator that is operative to engage the latch member of the leader block. The actuator is moveable between an active position wherein the actuator moves the catch piece into the open position and an inactive position wherein the restorative force of the latch member moves the catch piece into the closed position. As an example, the actuator may be a lever that is pivotally moveable between the active and inactive positions over a throw distance. The throw distance may be selectively adjustable. In order to advance the actuator from the inactive position to the active position, a cam is provided that pivots the actuator so that a prong portion of the actuator lever bears against the actuator tab on the latch member to pivot the first and second arms into the open position.
The present invention is also directed to a read/write apparatus adapted to receive spool of tape medium, such as a cartridge, and is operative to perform a read/write function thereon as the tape medium advances in a forward direction. The read/write apparatus of this invention includes a read/write recording head and first and second bearing members respectively located upstream and downstream of the read/write recording head in order to support the tape medium as it advances there across. The read/write apparatus includes a take up mechanism including a hub having an outer surface about which the tape medium is to be wound. A rotatable drive is then operative to rotate the hub thereby to wind the tape medium thereon. The read/write apparatus includes a threading assembly including a leader block adapted to engage the free end of tape member. While a leader block is constructed as described above, and the threading assembly can be as described above or other conventional threading assemblies.
Finally, the present invention is directed to a method of threading a tape medium from a tape source through a read/write recording apparatus wherein the tape medium has the leader pin associated therewith. The broad method of the present invention includes a step of advancing a releaseably latchable leader block into abutment with the leader pin and engaging the leader pin with the leader block. The method includes the step of latching the leader block to capture the leader pin therein and then advancing the leader block to a winding hub. The hub is rotated thereby to wind the tape medium thereon. After a portion of the tape medium has been wound on the hub, then method includes the step of rotating the hub to unwind the tape medium from the winding surface and to rewind the tape medium into the tape source. The leader block is returned to a location adjacent the tape source and leader pin is then unlatched from the leader block. In addition to these steps the exemplary method may also include the step of pressing the leader block against the leader pin to snap lock the leader pin therein to accomplish the step of latching the leader block to capture the leader pin. The step of unlatching the leader pin may be accomplished by advancing an actuator against a portion of the leader block to pivot a latch portion thereof out of engagement with a leader pin.
These and other objects of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of the exemplary embodiment of the present invention when taken together with the accompanying drawings, in which: